26 FREDERICK EBERSON 



toxin and gives rise to clinical symptoms known as diphtheria, for 

 which a specific antitoxin exists. 



C. pseudodiphtheriae sp. nov. (Fig. 10). Avirulent organism, 

 morphologically and culturally like C. diphtheriae but produces no 

 toxin and exerts no action when injected into animals. Isolated from 

 hypertrophied tonsils. 



GROUP 2. Pseudodiphtheriticum. Type C. pseudodiphtheriticum 

 (Hofmann-Wellenhoff.) Nonmotile, nonsporeforming, gram-positive, 

 does not liquefy gelatin. It is shorter and thicker than the C. diph- 

 theriae, but variations such as knobbed, clubbed and barred forms 

 occur. It is avirulent and produces no toxin. In carbohydrates, no 

 acid is produced. 



C. ceruminis (Graham Smith) Eberson. Differs somewhat from 

 C. pseudodiphtheriticum in morphology, as well as in its behavior in 

 broth which remains clear, with sediment. In carbohydrates, no acid 

 is produced. It is avirulent. Isolated from normal ear. 



C. delicatum sp. nov. (Fig. 6). Avirulent strains from ascitic 

 fluids and blood culture. The organism is small and delicate with a 

 decided preference for anaerobic conditions in the early generations. 

 Some strains form traces of acid in dextrose or maltose, but usually 

 ferment none of the sugars. 



GROUP 3. Xerosis. Type C. xerosis (Neisser and Kuschbert). 

 Nonmotile, nonsporeforming, gram-positive, does not liquefy gelatin. 

 Resembles C. diphtheriae closely morphologically. Acid is produced 

 in dextrose, saccharose and maltose. The organism can be isolated 

 from normal as well as diseased eyes. Growth solid medium is rather 

 delicate. 



C. epidermidis sp. nov. (Fig. 7). Gram-positive, facultatively 

 aerobic, non-sporeforming, does not liquefy gelatin. It is small ovoid 

 in form. Little growth takes place after one week at temperature 

 below 25 C. On Loeffler's serum abundant, dull white, growth. Slight 

 acid is produced in dextrose and maltose. It is avirulent. Isolated 

 from skin and pus pockets. 



C. suppuratum sp. nov. (Figs. 3, 4). Gram-positive, nonspore- 

 forming, does not liquefy gelatin. Heavy glistening growth on agar 

 and on Loeffler's serum. Ferments dextrose and maltose vigorously 

 and usually saccharose. Isolated from pus pockets and abscesses. 

 Avirulent. 



